The invention relates to a process for applying resilient clamping bands with lugs, particularly adapted to assembly lines for products such as flexible pipes particularly in the automotive field; the invention also relates to the tools for practicing the process.
The invention relates to clamping bands which are conventionally produced from a strip of sheet metal shaped as a generally circular ring. The ring in question is adapted to be deformed by spacing its two ends which creates a resilient return couple used for gripping; among these types of clamping bands are of particular interest those whose two ends of the spring band overlap; an intermediate cutout of the clamping band extends for several centimeters at one of its ends to form a passage for the other, which is decreased in width to coincide with said passage. The two ends of the band are provided with a drive lug obtained by simple right angle bending of its external portions outwardly of the band such that, thanks to a plier having jaws, the two control lugs can easily be brought together, which is to say to increase the diameter of the clamping band which produces, when released, the resilient return couple necessary for gripping, for example of a flexible pipe on a pipe system.
There exist numerous tools for mounting and unmounting such clamping bands, but they are very generally manually operated and independent; these tools must be of small size and particularly light in weight to fulfill effectively the speed required for present production lines.
Other problems also arise for these tools, which require the user to exert, for each mounted resilient clamping band, the force necessary at least for their expansion, even if they use lever systems greatly facilitating this operation, as is for example taught by French patent FR-96/16083.
It will accordingly be evident that it would be advantageous to have a mechanized device permitting instead to permit the user to pre-stress the resilient clamping bands before emplacement, without at the same time losing the advantage of small size of a strictly manual and independent application tool permitting rapid and precise positioning in an environment with very limited accessibility.
To this end, and according to the present invention, there is proposed for applying resilient clamping bands with lugs, particularly adapted to repeated mounting of flexible pipes on a pipe system, a process that it remarkable in that from a clamping band dispenser associated with a hand tool that is autonomous, forming the assembly of the tool for applying resilient bands, said tool being conventionally provided with two jaws shaped for gripping and bringing together the lugs of a clamping band to open it, the following successive steps being taken:
a) emplacing the jaws of the tool on the lugs of a first clamping band suitably positioned in the dispenser,
b) pre-locking the jaws of the tool bearing on the ears of said clamping band bringing it into the opening position thanks to mechanized actuation means,
c) self-holding the jaws in the pre-locking position thanks to internal means of the tool,
d) withdrawing from the dispenser said first clamping band held open by the hand tool and the correct automatic positioning of a second clamping band ready for a second extraction,
e) positioning the opened clamping band about the flexible pipe,
f) releasing the locking of the jaws of the tool which is provided for this purpose with control means to close the clamping band on the flexible pipe, and to cause its clamping on the pipe system, and releasing the tool for a new operation.
It will be easily understood that it is very interesting to have such a process that does not require the user to exert the energy necessary to pre-stress the resilient clamping bands before positioning on the piping, which instead is performed by an external device which can be automatically or manually controlled by the operator himself.
According to a preferred characteristic, the operation of pre-stressing the clamping bands taking place within the dispenser, the dangers of untimely ejection and breakage are eliminated, that are now observed with conventional hand tools at the time of insertion of the clamping bands between their jaws.
According to another object of the invention, there is provided a hand tool for extraction and positioning that is particularly adapted for use in the process described above. According to a first modification, such a tool comprises two confronting jaws, shaped to receive the lugs of a resilient clamping band and disposed at the end of two articulated legs to be disposed in a V shape so as to coact with the clamping band dispenser in a fixed position provided with its pre-compression system as has been mentioned; in this modification, the positioning tool is provided with a blocking system permitting freely and automatically the operation of the mechanism for bringing the jaws together to stress a clamping band and, on the contrary, preventing the reverse movement except when actuated by a control provided for this purpose to space apart automatically the movable jaws. According to this first modification, the release device for the jaws which will be described in greater detail hereafter, has no progressivity such that the positioning of the clamping band is extremely quick, which can lead in certain situations to a loss of precision in its positioning on the clamping zone. This is the reason why there are also provided two other modifications of the positioning tool that can use the process according to the invention, which permit a more progressive release of the jaws at the time of mounting the clamping band on the flexible pipes.
Thus, according to other modifications of the positioning tool, the latter comprises two legs provided, at one of their ends, with jaws and an articulation at the other to open freely under the action of the stress in the clamping band from a position in which they are close to each other or the jaws hold the compression of the clamping band, to a deployed position in a V configuration permitting the jaws to engage or disengage the lugs of the clamping band when the latter is respectively ready in the fixed dispenser, or discharge after its emplacement on the flexible pipe, coacting with means such that, when said legs are mounted slidably along their articulated ends in the direction of their longitudinal axis within and into abutment with a bottom of a casing, only the jaws emerge from the opening of said casing with which the legs coact to be held in closed position and stabilized by braking means; and conversely, when said legs are progressively slid outwardly under the controlled action of the force of the clamping band to a stop abutment near the opening of the casing, they deploy into a V configuration thanks to a resilient member acting against both of them.
The great advantage provided by these new modifications of the emplacement tool will be understood, in which the release of the jaws takes place in a progressive manner, or, according to a second modification, by a controlled retraction of the tool permitting progressive opening of the two arms and hence the release of the clamping band which, moreover, is necessarily in rear abutment against the passage to resist the retraction force (which prevents any lateral shift of the clamping band along the flexible pipe at the time of its mounting), or in a third modification by using preferably the external edges of the legs of said tool, which are used as a smooth track or partially bent to provide under the force of a compressed clamping band, respectively a free guiding and sliding on one leg and a free guiding or braking on the other leg by the bias of a regulation mechanism controlled such that the assembly of the two legs, beginning from their innermost position in abutment against the rear, wherein the clamping band is totally compressed, deploy progressively outwardly under the gradual and controlled action of said mechanism.
On the other hand, given that the position of a clamping band on piping takes place most of the time under cramped conditions (vehicle assembly line), it has to be taken into account that to mount a clamping band on a flexible pipe, there is seldom sufficient space to carry out an inclined or even perpendicular retraction relative to the piping, that would be necessary correctly to use the positioning tool.
To overcome this great drawback that can be encountered with the first two modifications, it has been proposed according to an essential characteristic of the third modification, to mount on the legs of the tool rotatable jaws so as to be able at least to incline the tool at the time of its retraction to release the clamping bands; it follows that such a situation cannot be controlled other than by the gradual control of the extension of the legs thanks to the release mechanism provided in the third embodiment.